Ceramic condensers

ABSTRACT

A ceramic condenser which comprises a combination of a cylindrical ceramic dielectric member having metal electrodes at both end surfaces and an insulator having a projection to be engaged in central through hole of the dielectric member. The member is provided with a connecting metal fixture as butted against one of the electrodes at the side opposite to the one receiving the insulator. A synthetic resin is molded around outer and inner peripheries of the dielectric member so as to expose the connecting metal member and the other electrode. The connecting fixture has a conductor extending through the central through holes of the dielectric member and the insulator, and threaded at its end so as to be fastened by means of a nut, so that a panel shape metal connecting plate will be held between the dielectric member and insulator as butted against exposed electrode of the member.

United States Patent [72] Inventors Shlro Ito;

Shoichi Iwaya, both of Tokyo, Japan [21] Appl. No. 889,215 [22] FiledDec. 30, 1969 [45] Patented Nov. 2, 1971 [73] Assignee TDK ElectronicsCompany, Limited Tokyo, Japan [32] Priorities Aug. 26, 1969 [33] Japan[3 1 44/80476;

Sept. 3, 1969, Japan, No. 44/815286; Oct. 8, 1969, Japan, No. 44/79991;Oct. 8, 1969, Japan, No. 44/95422; Nov. 25, 1969, Japan, No. 44/112334;Nov. 27, 1969, Japan, No. 44/112750 [54] CERAMIC CONDENSERS 3 Claims, 18Drawing Figs. [52] 11.5. CI. 317/256, 317/242, 317/261 [51] Int. Cl 01g1/03 [501 Field of Search 317/242, 256, 261

[56] References Cited UNITED STATES PATENTS 2,922,936 1/1960 Dehnm'317/242 2,983,855 5/1961 Schlicke 317/242 FOREIGN PATENTS 943,57112/1963 Great Britain 317/242 Primary ExaminerE. A. GoldbergAttorney-Wolfe, Hubbard, Leydig, Voit & Osann ABSTRACT: A ceramiccondenser which comprises a combination of a cylindrical ceramicdielectric member having metal electrodes at both end surfaces and aninsulator having a projection to be engaged in central through hole ofthe dielectric member. The member is provided with a connecting metalfixture as butted against one of the electrodes at the side opposite tothe one receiving the insulator. A synthetic resin is molded aroundouter and inner peripheries of the dielectric member so as to expose theconnecting metal member and the other electrode. The connecting fixturehas a conductor extending through the central through holes of thedielectric member and the insulator, and threaded at its end so as to befastened by means of a nut, so that a panel shape metal connecting platewill be held between the dielectric member and insulator as buttedagainst exposed electrode of the member.

Pmmtnuuvz 1971 -35175'632 SHEETBUF 3 INVENTORS Sumo I TO SHOICHI IWAYAATTORNEYS CERAMIC CONDENSERS This invention relates to ceramiccondensers.

Recently, high electric powers of UHF or VHF are utilized not only forsuch industrial purposes as of broadcasting apparatuses and the like butalso for such daily uses as of microwave ovens and the like.

. However, with the increase of such utilization, the problems ofreceiving faults in television and radio apparatuses and fielddisturbances in general communication apparatuses due to field noisesleaking out of such apparatuses have come to be considered important andcountermeasures have been taken against them.

That is, there is required a filter which is different in the use from aconventional filter in respect that a high voltage and high electricpower are impressed. For such purpose, there has been used a filtercombining a disk-shaped ceramic condenser insulatively molded to be highin the voltage resistance with a coil. However, in such disk-shapedceramic condenser, there is a clearance between the earthing sideelectrode and chassis and they are connected through a fine metallicterminal. Therefore, at a high frequency, due to the inductancecomponent of the metallic terminal, the condenser does not operate as acapacitor. For such reason as the leakage due to an undesirableradiation, its characteristic as of a filter does not satisfy therequirement. Its early improvement has been required.

The present invention has been suggested to meet the above requirement.

A main object of the present invention is, therefore, to provide acondenser which has a high voltage resistance and can operate at a highefficiency as a capacitor until a high frequency with the earthing sideelectrode directly in close contact with the chassis.

Another object of the present invention is to provide a condenseradapted to a filter for high voltages.

Other objects and advantages of the present invention will becomeapparent upon reading the following descriptions set forth withreference to accompanying drawings, in which:

FIG. 1 is a plan view of the mold section of a ceramic condenseraccording to the present invention, shown partly in section.

FIG. 2 is a sectioned view of the mold section taken along line IL-1] inFIG. 1.

FIG. 3 is a plan view of an insulator to be combined with the moldsection of FIG. 1.

FIG. 4 is a sectioned view of the insulator taken along line IV-IV inFIG. 3.

FIG. 5 is a sectioned view showing the ceramic condenser of theinvention as assembled with the mold section and insulator of FIGS. l-4.

FIG. 6 shows an example of the use of the ceramic condenser.

FIG. 7 shows attenuation characteristics of a filter using aconventional ceramic condenser.

FIG. 8 shows attenuation characteristics of a filter using the ceramiccondenser of the present invention.

FIGS. 9 through 14 shown another embodiment of the present invention, inwhich:

FIG. 9 is a plan view partly in section of a ceramic condenser;

FIG. 10 is a sectioned view taken along line X-X in FIG. 9;

FIG. II is a sectioned view of a mold section of the ceramic condenserin FIGS. 9 and 10;

FIG. 12 shows in section an insulator of the ceramic condenser in FIGS.9 and I0;

FIG. 13 shows a bolt used in the same; and

FIG. 14 shows a nut in the same;

FIGS. 15 and 16 show another embodiment of the present invention, inwhich:

FIG. 15 is a plan view partly in section of the same; and

FIG. 16 is a sectioned view taken along line XVI-XVI in FIG. 15.

FIG. 17 and 18 show a further embodiment of the present invention, inwhich:

FIG. 17 is a plan view shown partly in section; and

FIG. 18 is a sectioned view taken along line XVIII-XVIII in FIG. 17.

While the present invention shall how be disclosed in detail withreference to certain embodiments as illustrated, it should be understoodthat the invention is not to be limited to the particular embodiment butis rather intended to include all of possible modifications, alterationsand equivalent arrangements to be included in the scope of appendedclaims.

In FIG. 1 to 5, 1 is a thick cylindrical ceramic dielectric and 2 and 3are electrodes formed on both end surfaces of it. Any of the followingmethods is used in forming the electrode:

1. A method wherein flit glass as mixed with a metallic silver powder ofsilver oxide powder and kneaded to be pasty is screen-printed, sprayedwith a spray gun or manually applied with a brush on the dielectric, isdried and is baked at a temperature above 500 C., to be an electrode.

2. A method wherein a metallic lamina is punched on the dielectric andis bonded thereto with a conductive binder to form an electrode.

3. A method wherein a conductive resin is screen-printed, sprayed with aspray gun or manually applied with a brush on the dielectric and isbaked above 150 C. to be an electrode.

4. A method wherein a nonelectrolytic plating of Ni is applied to thedielectric surface and the plating in the unnecessary part is scrapedoff with a centerless grinder or the like.

5. 5. A method wherein an Ni-Cr alloy or the like is vacuum evaporatedon to the dielectric.

6. A method wherein Mn-M4 is baked on the dielectric.

0f the electrodes provided as mentioned above, the electrode 3 becomesan earthing side electrode and a disk-shaped connecting metal fixture 5having a through hole in the center is bonded to the other electrode 2by soldering or with a conductive binder.

6 is such synthetic resin as an epoxy resin, silicone resin or the like,or a mixture of such synthetic resin with Si0,, Ti0,, A1 0 mo, or thelike as a filler, as molded by casting on the inner and outer peripheralsurfaces of the ceramic dielectric one in order to improve theinsulation and such reliabilities as the voltage resistance anddamp-proofness. In such case, the .end surfaces of the electrode 3 andconnecting metal fixture 5 are exposed out of the molded part 6.

As shown in Fig. 3 and 4, 7 is an insulator having a through hole 8 anda projection 9 and made of such ceramic insulator as steatite,forsterite or the like, or such synthetic resin as an epoxy, phenolresin or the like.

13 is a bolt which is a through conductor made by threading such a metaleasy to work as brass and plating it with such metal as Ni, Ag, Cr, Cdor the like, and is to hold the molded and through ceramic condenserpart to a chassis. 10 is a nut screwed to the bolt 13 and 11 is awasher.

FIG. 5 shows an assembly in which the earthing side electrode 3 is keptin close contact with one side of a chassis 12, the projection 9 of theinsulator 7 is inserted into the center hole of the molded part 6 andthe nut 10 is screwed through the washer 11 to the forward end of thebolt 13 put into the center hole of the molded part 6.

Thus, according to the present invention, the earthing side electrode ispressed into contact directly with the chassis 12 through the connectingmetal fixture 5 so that no inductance component will be contained evenat a high frequency and a condenser having little undesirable radiationcan be obtained.

Fig. 6 shows an example of the use of the present invention.

Fig. 7 shows an example of the frequency-attenuation characteristics ofa filter using a conventional condenser.

Fig. 8 shows attenuation characteristics of a filter made by combininganother inductor with a capacitor of the present invention. Anattenuation of about db. is obtained therein. The characteristics by thesame inductor and a conventional capacitor are such as in Fig. 7 atmost. Even in the light of this, it will be understood that, in to L000MHL, an attenuation about twice as large as by the combination of theconventional capacitor is obtained when the capacitor according to thepresent invention is used. Thus, according to the present invention, theleakage of electromagnetic waves out of the apparatus can be preventedvery effectively.

Further, an electronic circuit which is resistant to a highvoltage andhigh-electric power is obtained. The gain of the circuit is high. Thus,the practical advantage when it is used for microwave ovens or the likeis very high.

Figs. 9 to 14 show another embodiment of the present invention. In thedrawings, 1 is a cylindrical ceramic dielectric, 2 and 3 are electrodesand 14 is a connecting metal fixture having a through hole in thecenter, disk-shaped in the bottom, cylindrical in the body and bonded tothe electrode 2. 15 is a ring-shaped connecting metal fixture bonded tothe electrode 3. 6 is an insulating mold made cylindrical so as toenclose the ceramic dielectric l, electrodes 2 and 3 and connectingmetal fixtures l4 and 15. But, the outside (left side in the drawings)of the connecting fixture 14 and the inside of the ring-shapedconnecting fixture 15 are not enclosed with the mold 6. This state isshown in Fig. ll. 7 is an insulator having a through hole 8 and aprojection 9. 10 is a washer, 13 is a nut, and 12 is a chassis. They areassembled substantially the same as in the preceding embodiment. Theassembly is shown in Fig. 10.

Fig. 15 and 16 show a further embodiment. In the drawings,

l is a ceramic dielectric, and 2 and 3 are electrodes. 16 is aconnecting metal fixture having a through conductor at right angles withthe body in the middle and threaded 17 in the respective end parts. Thisconnecting metal fixture 16 is inserted and bonded to the electrode 2.19 is a square panelshaped connecting metal fixture having a hole in thecenter. The earthing electrode 3 is bonded to the outer periphery ofthis hole. A small fitting hole is made in each of the four corners ofthis connecting metal fixture 19. The connecting metal fixtures l6 and19 are molded so as to form the molded part 6 as bonded to theelectrodes on the respective end surfaces of the ceramic dielectric l.The molding material to be used is the same as in the case of the firstembodiment.

Fig. 17 and 18 show another embodiment. An electrode is formed at eachend of each of two cylindrical ceramic dielectrics l, a connecting metalfixture 16 having a through conductor and threaded in the end parts 17and 18 is bonded to one electrode 2., a common connecting metal fixture19 having two holes is bonded to the other electrode 3 and the ceramicdielectrics l are molded so as to form a synthetic resin molded part 6.

What is claimed is:

l. A ceramic condenser comprising in combination a cylindrical member ofa ceramic dielectric, a pair of first and second metallic electrodesformed independently on the respective end surfaces of said ceramicdielectric member, a connecting metal fixture having a through hole inthe center and an outer surface and being bonded to said firstelectrode, a molded part of a synthetic resin enclosingcircumferentially said ceramic dielectric and said first metallicelectrode, said second electrode and said outer surface of saidconnecting metal fixture being spaced outside of said molded part, saidmolded part being provided in the center with a through hole, and acylindrical insulator having a flange provided in the center with aprojection to be inserted in said through hole of the molded part andwith a through hole in the center, said insulator being adapted to holda chassis member between its surface around said projection and theexposed second electrode on the ceramic dielectric member.

2. A ceramic condenser comprising in combination a cylindrical member ofa ceramic dielectric, a pair of first and second metallic electrodesformed independently on the respective end surfaces of said ceramicdielectric member, a first connecting metal fixture bonded to said firstelectrode, said metal fixture having a through hole in the center andhaving a disk-shaped inner member and a cylindrical-shaped outer member,a second ring-shaped connecting metal fixture bonded to said secondelectrode and having an outer surface,

a molded part of a synthetic resin enclosing circumferentially saidceramic dielectric, a portion of said cylindrical-shaped outer member ofsaid first connecting metal fixture and said outer surface of saidsecond connecting metal fixture being spaced outside of said moldedpart, said molded part being provided in the center with a through hole,and an insulator provided in the center with an axial projection to beinserted in said through hole of the molded part and with an axialthrough hole in the center, said insulator being adapted to hold achassis between its surface around said axial projection and the exposedsecond metal fixture on the ceramic dielectric member.

3. A ceramic condenser comprising in combination a cylindrical member ofa ceramic dielectric, a pair of first and second metallic electrodesformed independently on the respective end surfaces of said ceramicdielectric member, a first connecting metal fixture inserted into theceramic dielectric member and bonded to said first electrode, said firstconnecting metal fixture having an axial through conductor threaded onboth extended end parts, a second panel-shaped connecting metal fixturebonded to said second electrode and having means to connect the secondfixture to a chassis, and a molded part of a synthetic resin insulatorenclosing circumferentially said ceramic dielectric, said threaded endparts of the first metal fixture and said connecting means of the secondmetal fixture being spaced outside of said molded part.

1. A ceramic condenser comprising in combination a cylindrical member ofa ceramic dielectric, a pair of first and second metallic electrodesformed independently on the respective end surfaces of said ceramicdielectric member, a connecting metal fixture having a through hole inthe center and an outer surface and being bonded to said firstelectrode, a molded part of a synthetic resin enclosingcircumferentially said ceramic dielectric and said first metallicelectrode, said second electrode and said outer surface of saidconnecting metal fixture being spaced outside of said molded part, saidmolded part being provided in the center with a through hole, and acylindrical insulator having a flange provided in the center with aprojection to be inserted in said through hole of the molded part andwith a through hole in the center, said insulator being adapted to holda chassis member between its surface around said projection and theexposed second electrode on the ceramic dielectric member.
 2. A ceramiccondenser comprising in combination a cylindrical member of a ceramicdielectric, a pair of first and second metallic electrodes formedindependently on the respective end surfaces of said ceramic dielectricmember, a first connecting metal fixture bonded to said first electrode,said metal fixture having a through hole in the center and having adisk-shaped inner member and a cylindrical-shaped outer member, a secondring-shaped connecting metal fixture bonded to said second electrode andhaving an outer surface, a molded part of a synthetic resin enclosingcircumferentially said ceramic dielectric, a portion of saidcylindrical-shaped outer member of said first connecting metal fixtureand said outer surface of said second connecting metal fixture beingspaced outside of said molded part, said molded part being provided inthe center with a through hole, and an insulator provided in the centerwith an axial projection to be inserted in said through hole of themolded part and with an axial through hole in the center, said insulatorbeing adapted to hold a chassis between its surface around said axialprojection and the exposed second metal fixture on the ceramicdielectric member.
 3. A ceramic condenser comprising in combination acylindrical member of a ceramic dielectric, a pair of first and secondmetallic electrodes formed independently on the respective end surfacesof said ceramic dielectric member, a first connecting metal fixtureinserted into the ceramic dielectric member and bonded to said firstelectrode, said first connecting metal fixture having an axial throughconductor threaded on both extended end parts, a second panel-shapedconnecting metal fixture bonded to said second electrode and havingmeans to connect the second fixture to a chassis, and a molded part of asynthetic resin insulator enclosing circumferentially said ceramicdielectric, said threaded end parts of the first metal fixture and saidconnecting means of the second metal fixture being spaced outside ofsaid molded part.